Nuclear Construction Use of Welding

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Nuclear Lessons LearnedGuidance on Best Practice: Welding

Engineering the Future

Nuclear Construction Lessons LearnedGuidance on best practice: welding

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© The Royal Academy of Engineering

ISBN: 1-903496-82-9

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April 2012Published byThe Royal Academy of Engineering3 Carlton House TerraceLondon SW1Y 5DG

Tel: 020 7766 0600 Fax: 020 7930 1549www.raeng.org.ukRegistered Charity Number: 293074

A copy of this report is available online at:www.raeng.org.uk/ncllweldingwww.ice.org.uk/nuclearbestpracticeguideswww.engineeringthefuture.co.uk/government/

Nuclear Construction Lessons Learned

Guidance on best practice: welding

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Foreword..........................................................................................................3

1. Introduction .................................................................................................5

2. Welding quality assurance .........................................................................6

3. Welding skill requirements .......................................................................12

4. Introduction of new technology..................................................................15

5. Conclusions................................................................................................17

Acknowledgements .......................................................................................18

References .....................................................................................................19

Contents

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ForewordThe achievement of the UK government’s challenging carbon reductiontargets will be directly related to the successful delivery of a fleet of newnuclear power stations. In support of this, Engineering the Future, followinga request from the Department of Energy and Climate Change and theOffice for Nuclear Development, set up a steering group to examine thelessons that could be learned from recent civil nuclear power plantconstruction projects. The project steering group was formed byrepresentatives from relevant engineering institutions and bodies andconsidered both the lessons that could be learned and how they should beincorporated into the proposed UK new build programme. In October 2010the project steering group delivered a report to Charles Hendry MP,Minister of State for Energy & Climate Change, on the construction lessonslearned from six international nuclear new build projects.

The purpose was to help UK industry to fully understand the issues thathad led to delays, rework and redesign in past nuclear build projects; andincorporate that learning into new build projects and thus reduce delaysand increase investor confidence.

The Nuclear Lessons Learned1 study examined experiences from six recentnuclear construction projects and established five general lessons:

1. Follow-on replica stations are cheaper than first of a kind.

2. The design must be mature and licensing issues resolved prior to start ofconstruction.

3. A highly qualified team should be established to develop the design,secure the safety case, plan the procurement and build schedule incollaboration with the main contractors.

4. Subcontractors should be of high quality and experienced in nuclearconstruction, or taught the necessary special skills and requirements forquality, traceability and documentation.

5. Good communications with the community local to the site should beestablished and maintained.

Once these general lessons were established, an industry stakeholder groupmeeting in November 2010 suggested to the steering group that a focus onspecific areas of nuclear construction would be of particular use to industry.It was decided that the first three of these ‘deep dives’ would cover nuclearsafety culture2, concrete3 and welding. Working groups led by the most relevantprofessional engineering institutions took these topics forward, producingbest practice guidance documents for each. Industry was widely consultedon the draft guidance documents, which were finalised following a workshopheld on 19 September 2011.

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The Nuclear Safety Culture2 best practice document presents anoverarching view of safety culture in the context of a new nuclear buildprogramme. The recommendations of that specific report apply to allaspects of nuclear construction. The Concrete3 guide looks at the use ofconcrete in nuclear construction. This report addresses best practice inrelation to welding.

The aim of these best practice guides is to provide accessible informationto help those involved in nuclear construction projects to adopt behavioursconducive to successful project delivery. Although they are not intended tobe standards, codes of practice or contract conditions, the members of theEngineering the Future alliance believe that following the recommendationswill be beneficial to companies in terms of delivering new nuclear projectsto cost and programme.

A consistent approach is important given the degree of subcontractingprevalent in the UK market, as the success of the project relies on all thoseinvolved throughout the supply chain.

The guidance documents are aimed at all those within the supply chainwishing to better understand the demanding requirements of nuclearconstruction. The documents are particularly relevant to those whose rolesencompass the design, specification, tendering and bidding for work withinnuclear construction projects, as well as those responsible for delivery. Therecommendations should prove selectively useful for those developingbusiness strategies through to those working onsite.

Through these documents, Engineering the Future seeks to facilitate learningfrom previous construction events to help create a strong and successfulnew nuclear build programme in the UK.

During the nuclear new build programme further lessons will surface. It willbe important to ensure that an effective mechanism is in place to captureand disseminate this learning. This process will further contribute to theeffective delivery of a fleet of new nuclear power stations.

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1. IntroductionThe Welding Institute (TWI) chaired a working group on welding quality,which identified the welding-related issues reported in the Nuclear LessonsLearned1 report, and used that as the basis for reviewing andrecommending actions to help ensure that welding is of the requisitequality across the whole new build fleet programme.

Many of the recommendations in this report highlight the need forintegrated, collaborative and, in some cases, ‘top-down’ solutions to issuesof welding quality, skills development and the implementation of newtechnology. While compelling stakeholders to participate in such cross-cutting initiatives is neither feasible nor desirable, solutions will only besuccessful if they are developed by the nuclear industry for the nuclearindustry. In this regard, collaboration and knowledge sharing across thenuclear industry are key.

Recommendation 1

A forum for sharing knowledge and good practice on welding in nuclearpower facilities should be established, with membership from industryand expert bodies, such as TWI. It should focus on the nuclear industrybut have knowledge of practices in other relevant industries such as oiland gas. This forum should have clear terms of reference anddeliverables for example gathering and disseminating data on thecapabilities of new technologies.

Welding issues in Nuclear Construction LessonsLearned report

Welding issues and related topics appear in several of the projectsexamined in the original Nuclear Lessons Learned1 report. It is important torecognise that issues within welding itself cannot be viewed in isolationfrom related topics such as overall approaches to quality assurance (QA)and skills shortages.

The issues the working group identified were:

• welding integrity and control of welding operations

• introducing new technologies

• overall approach to quality assurance (QA)

• contractor management

• skills shortages

• project management

• construction approach, for example onsite, offsite and modular

To meet the steering group’s requirement for brevity in the final report, theworking group combined these issues into three topics for discussion andrecommendation: welding quality assurance, welding skills and introducingnew technologies. This approach was approved by the steering group.

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2. Welding quality assuranceImportance of high quality welding

Welding is a manufacturing process that is critical for the successfulconstruction and safe operation of nuclear power plants. With theprevalence of fabricated metallic components such as pressure vessels,pipe work, liners and cable trays, the scale of the welding task is very largefor both onsite and offsite fabrication. For example, on the Olkiluoto EPRbuild project there are approximately 200km of piping and about 30,000welds within the nuclear island alone4. Industry and other stakeholdersmust be confident of the quality and integrity of welded joints, particularlyas the next generation of nuclear power plants is expected to have a designlife of at least 60 years.

Ensuring welding quality is challenging and can be costly. Most often it isexamined in the finished product and in instances where quality criteria arenot met; costly and time-consuming repair and rework can result.Approaches used in other industries that address quality assurance in thewelding process may be applicable to nuclear. These are examined in thissection.

ASME and RCC/ETC codes/standards

Two sets of rules are in use worldwide which apply to nuclear significantpressurised components: in the nuclear industry5; these rules are publishedby ASME6 (American Society of Mechanical Engineers) and AFCEN7

(French Association for the rules governing the Design, Construction andOperating Supervision of the Equipment Items for Electro Nuclear Boilers).It is likely that both approaches will be used for UK new build, with ASMEstandards for builds using Westinghouse’s AP1000 technology andRCC/ETC publications used for builds using Areva’s EPR.

Both codes have significant implications for welding quality and integrity,and this is set out in more detail below.

• ASME

In the United States, the Nuclear Regulatory Commission (NRC) isresponsible for licensing and monitoring the operation of nuclear utilitypower plants throughout the USA under legislation passed by Congressunder the Code of Federal Regulations. Requirements binding on allpersons and organisations that receive a licence from NRC to use nuclearmaterials or operate nuclear facilities are mandated in Title 10 of the Codeof Federal Regulations8. Appendix B to Section 50, Title 10 (10 CFR 50Appendix B). This contains the 18 quality assurance criteria that the nuclearplant operator must meet. Plant operators pass these requirements downto their suppliers providing materials, services, equipment, software orother products for the operation of the facility. Paragraph IX of thisAppendix (Control of special processes) states:

“Measures shall be established to assure that special processes, including welding,heat treating, and non-destructive testing, are controlled and accomplished byqualified personnel using qualified procedures in accordance with applicable codes,standards, specifications, criteria, and other special requirements.”

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ASME standard for Quality Assurance Requirements for Nuclear FacilityApplications (QA) - NQA-1 (2004)9 provides supplemental information andcontract requirements on implementing the requirements of 10 CFR 50Appendix B. This standard provides guidance and methods for defining aquality system that would meet the legislative requirements. It is also aglobally recognised quality standard that organisations planningconstruction to the ASME code may want to adopt. This standard reflectsindustry experience and current understanding of the quality assurancerequirements necessary to ensure safe, reliable and efficient utilisation ofnuclear energy, and management and processing of radioactive materials.It covers the QA requirements for nuclear facility applications and isincluded by reference in the ASME Boiler and Pressure Vessel (BPV) Codeand other national standards.

While the NQA-1 standard can stand alone as the definitive QA standard,its use is promoted principally through endorsement and adoption byothers. The latest edition of NQA-1 is endorsed in all ASME nuclear codesand standards (NCS), such as ASME Boiler and Pressure Vessel CodeSection III (2010)10 and ASME power piping standard B31.1 (2010)11, so thatQA requirements for all NCS can be found in a single NQA-1 edition.However, the standard does not provide specific quality requirements forspecial processes.

The ASME Nuclear Component Certification program (ASME ‘N’ stamp)covers the equipment (such as nuclear vessels, pumps, valves, pipingsystems, storage tanks, core support structures, concrete containmentsand transport packaging) and activities (such as field installation and shopassembly, fabrication with or without design responsibility for nuclearappurtenances and supports), as covered by Section III of the ASME Boilerand Pressure Vessel Code. ASME ‘N’ stamp holders are subject toindependent monitoring of special processes (welding, heat treatment,Non-Destructive Examination) by an ASME Authorised Nuclear Inspector(ANI). Following the award of the ASME Certificate of Authorisation tomanufacturers/installers of nuclear and non-nuclear components, theauthorised inspector will be responsible for monitoring the manufacturer’squality programme, performing the required Code inspections, andattending further ASME renewal reviews.

• The RCC and ETC approach

The RCC (Rules for Design and Construction) family and ETCs (EPRTechnical Code) are a set of design and construction or technical codesand standards corresponding to industrial practice implemented in thedesign, construction and commissioning of the Areva EPR reactor. TheRCC rules for pressurised equipment of PWR nuclear islands primarilyapply to safety class components. In the UK new build programme, theRCC and ETC rules will be used on the EDF/Areva projects, at HinkleyPoint C and Sizewell C. The rules given in the Design and Conception Rulesfor Mechanical Components of PWR Nuclear Islands (RCC-M) draw primarilyon development work undertaken in France. It has been upgraded severaltimes since the promulgation of the standard in 1981, and in 2007, RCC-Mstandards were subject to a major upgrade. This upgrade focused on therenewal of EU standards referenced in all chapters to ensure consistencywith EU requirements, and to meet recognised international standards.RCC-M requires product and shop qualification and also prototypequalifications. As with ASME NQA-1, RCC-M, Section 1 specifies broad QAand quality management requirements based on the ISO 9001 requirements.

In the construction phase of Sizewell B, adaptation documents werewritten to bridge the particular definitions of terminology, key responsiblepersonnel, and their roles and responsibilities as given in the Americancodes so that these could be applied to a European/British context.

Recommendation 2

For fabrication of components, ASME and RCC-M ‘equivalence’ or‘adaptation’ documents may need to be written, similar to those usedfor the construction of Sizewell B, which will establish how qualitywelding requirements will be implemented in a UK context andarrangements made to cascade them through the supply chain.

• Other codes and standards

Other codes and standards will also apply, notably as a result of theEuropean context of the UK new build programme (at both the regulatoryand industrial level). These codes and standards can supersede existingRCC or ETC standards for certain technical areas and within a clearlydefined scope of application. They relate in particular to technical areassuch as pressurised equipment. In addition to these requirements, furtherregulatory requirements may be provided by the national authorities for thecountry where the nuclear equipment is installed (if existing). For example,in Finland, compliance with national Regulatory Guides on nuclear safety(YVL) is mandatory; while in France ESPN Order (2005) is now mandatoryfor new plant. This order defines those components which have to beconsidered as nuclear-specific according to the Pressure EquipmentDirective (PED). Such components are classified in three categories on thebasis of the failure potential and the associated activity release potential. Acomprehensive analysis of the QA/QC requirements imposed by variousregulations concerning conventional pressure equipment and nuclearpressure equipment in nuclear power plant projects and detaileddiscussion on the status of different codes in an international context hasbeen published by AFCEN12.

• The UK regulatory approach

The Office for Nuclear Regulation (ONR) grants nuclear site licences onbehalf of the Health and Safety Executive (HSE). The nuclear site licence isa legal document which contains site-specific information and iscomplemented by a set of 36 Standard Conditions covering design,construction, operation and decommissioning. These conditions requirelicensees to implement adequate arrangements to ensure compliance.They do not relieve the licensee of the responsibility for safety. They are,generally, non-prescriptive and set goals that the licensee is responsible formeeting, among other things, by applying detailed and appropriate safetystandards and safe procedures for the facility. The arrangements, which alicensee develops to meet the requirements of the licence conditions,constitute elements of a nuclear safety management system. ONR reviewsthe licensee’s licence condition compliance and implementationarrangements to see they are clear and unambiguous and address themain safety issues adequately.

The ONR and the Environment Agency developed the Generic DesignAssessment (GDA) process in response to a request from the UKgovernment following its 2006 Energy Review. In their contributions to the2006 Energy Review, the ONR and Environment Agency set out proposalsto assess new nuclear reactor designs in advance of any site-specific

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proposals to build nuclear power stations. The GDA process allows theregulators to get involved with designers at the earliest stage, where theyhave most influence and is a step-wise process, with the assessmentsgetting increasingly detailed. This allows the regulators to identify issuesearly in the process and reduce the project and regulatory risks for potentialoperators. Design issues are separated from specific site related issues,improving the overall efficiency of the regulatory process. At the end of theGDA process, the regulators will decide if the proposed designs areacceptable for build in the UK.

• ISO 9000 certification

The ISO 9000 family of standards represents an international consensuson good quality management practices. These standards provide a set ofuniform requirements for a quality management system, regardless of whatthe user organisation does, its size, or whether it is in the private or publicsector. ISO 9000 certification of a supplier of goods or services is one ofthe criteria that is often required by a purchaser to qualify them for a tenderor to achieve preferred supplier status. Welding is defined by ISO 9000 asa ‘special process’, whereby the quality of the product cannot bedetermined by a final inspection but must be assured by close control ofthe welding operation and its associated activities. ISO 9000 does notprovide any guidance or recommendations for quality assurance of thewelding process. Where significant use is made of a special process suchas welding, compliance with ISO 9000 is unlikely to provide the assurancethat the processes and products are of the required quality, as ISO 9000does not provide a framework for quality assurance in welding.

Approaches to welding-specific quality assurance

• ISO 3834 framework

To fill the gap in the ISO 9000 requirements for welding, a series ofspecifications have been published: ISO 3834 – Quality Requirements forWelding, Parts 1 to 4, and ISO 14731 Welding Coordination. Adopted bycompanies that serve high-integrity, safety-critical sectors such as oil andgas, construction and in some cases nuclear, the ISO 3834 series lists thequality assurance and quality control requirements necessary to ensure aproduct of the desired quality. ISO 14731 lists the requirements for thepersonnel performing and controlling welding and its related activities.

ISO 3834 has been published to specify what is regarded as best practice inthe control of welding. It is available to companies to provide a frameworkfor their welding quality management systems to ensure that weldingprocesses are carried out in the most effective way and that appropriatecontrol is exercised. Acceptable quality cannot be inspected into the weldedproduct, but is the result of careful control of each of the activitiesassociated with welding. As such, a quality management system forwelding should address all stages from design, material selection,manufacture and inspection and, if required, rectification or re-work.

ISO 3834 provides details not only of how to control the various weldingand welding-related operations to achieve consistently the desired qualitybut also the requirement to ensure that people with weldingresponsibilities are competent to discharge those responsibilities.

If the appropriate quality is to be achieved then there is a need for aframework specifying quality requirements in a tiered manner with respectto the control of special processes such as welding and its related

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activities, over and above those in ISO 9000, ASME and RCC/ETC codesand standards. Also, quality systems must identify and assess allmanufacturers in the entire supply chain to ensure standards areconsistently being achieved.

• Aerospace – Nadcap Accreditation and Nadcap Users Compliance andAudit Program (NUCAP) Approval

The aerospace sector is similar to the nuclear industry in terms of the valueplaced upon safety and quality requirements. In aerospace, AS9100 is thestandard for quality management systems (similar to ISO 9000).Additional requirements are implemented for the control of specialprocesses (examples include welding, inspection, post weld heat treatment(PWHT), coatings, chemical processing and testing). These are set out indocuments created for the Nadcap or NUCAP programmes. Theseprogrammes are administered globally through the Performance ReviewInstitute (PRI), a not-for-profit organisation.

Prior to 1990, the major aerospace companies were auditing their ownsuppliers for technical proficiency in areas such as non-destructive testing,welding and heat treatment. This meant a significant workload for theaerospace tier one manufacturers (for example Boeing and Airbus),duplicate audits for suppliers, and auditors were often forced to becomegeneralists to accommodate the workload. In addition, the industry foundthat quality management system audits did not adequately addressconcerns regarding special process competency and ability to meetindustry and customer requirements.

In 1990, Nadcap was established by key aerospace industry and USgovernment representatives, administered by PRI. Boeing mandatedNadcap accreditation to its supplier base in 2002, with Airbus following in2003.

Today, Nadcap represents an unprecedented, cooperative industry effort toimprove quality while reducing costs throughout the aerospace anddefence industries. It is an approach to conformity assessment that bringstogether technical experts from all over the world to establish requirementsfor accreditation, approving suppliers and defining operational programmerequirements. Being industry managed, Nadcap continuously drivesimprovements in the entire supply chain and makes it a supplier selectioncriterion for any organisation involved in providing goods and servicesinvolving special processes in the aerospace industry.

The major aerospace manufacturers control the structure of Nadcap bybeing part of the PRI board of directors; they also have representation onthe Nadcap Management Council (which implements policy and managesthe programme) as well as individual Task Groups (which define technicalrequirements and make the final decision on supplier accreditation) foreach special process, utilising technical representatives from eachsubscribing prime. The NUCAP programme complements the Nadcapprogramme by assessing the primes themselves to the same stringentNadcap requirements.

A key driver for Nadcap’s success is that it is a global, collaborative pan-industry initiative rather than something adopted partially on a narrownational basis.

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Recommendation 3

For the nuclear industry to satisfactorily implement a tiered weldingquality management system in the UK (based on ASME and/or RCC-Mcodes), it may be beneficial to review the experience of other sectors inimplementing the Nadcap and ISO3834 schemes and in considering anoverarching strategic management of quality assurance of welding as aspecial process.

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3. Welding skills requirementsHigh quality welding on nuclear construction projects and subsequent safeoperation are critically dependent on having suitably trained anddemonstrably competent personnel at all levels of the supply chain. Thisrequirement extends beyond direct welding personnel to relatedoccupations such as welding supervisors, welding coordinators andwelding engineers.

Nuclear new build labour market intelligence has noted that high integritywelders are a high risk skills shortage category . While welders have beenidentified as a critical skills shortage, labour market intelligence does notindicate which other welding roles are particularly affected (for examplewelding supervisors, welding coordinators and welding engineers).

Recommendation 4

The relevant skills bodies, in conjunction with supply chain companiesand The Welding Institute, need to provide detailed labour marketintelligence for welding role shortage to enable planning of trainingprogrammes. This should extend beyond craft-based skills toencompass higher level skills (for example beyond NQF level 4) such aswelding engineering.

Underlying causes of this shortage are many and include an ageing andretiring workforce and demand from competing sectors such as oil and gasand the introduction of offshore wind energy generation. There has alsobeen anecdotal evidence to show that school leavers and graduates totending to opt for non-engineering careers.

The supply of new entrant welding labour, for example apprentices, to thenuclear industry is currently hampered by a lack of certainty over the timingof contracts. There are examples of good practice in industry, with somecompanies running apprenticeship recruitment programmes in advance ofcontracts being placed. However, this is mostly confined to largercompanies. Smaller firms are unlikely to invest in costly apprenticeprogrammes in advance of orders being placed. Most fabrication workavailable to UK contractors will be several tiers down the supply chain, wherethe lack of suitably qualified and experienced personnel is most likely.

Recommendation 5

Where possible, operators, reactor vendors and major supply chaincompanies should consider early contracting with smaller fabricationcompanies to provide some certainty of return on investment in newskills and technology.

Recommendation 6

Operators, reactor vendors and major supply chain companies,supported by the relevant professional Institutions, should presentrecommendations to DECC and BIS for providing more significant‘pump priming’ funding to welding apprenticeship schemes to de-riskapprenticeship investment.

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The welding skills shortage will be exacerbated by the recent policy decisionto exclude welders from outside the EU from the Immigration NationalOccupational Shortage List14. When combined with factors statedpreviously, the policy decision to exclude welders is likely to have a negativeimpact upon the provision of suitably qualified, competent andexperienced welding personnel for UK new build, particularly at the time ofpeak demand (2018 to 2022). The potential implications of this areincreased costs, as a result of higher remuneration levels and project delays.

Recommendation 7

The welding industry should actively encourage government to giveconsideration to maintaining high integrity welding on the ImmigrationNational Occupational Shortage List by the Migration AdvisoryCommittee, with appropriate measures taken to ensure immigrantwelders are qualified to the same level as the existing UK work force.

Competence and experience in welding are as critical as qualifications. Theevidence of competence in the production of a weld will vary according tothe safety categorisation of each component. ONR has issued guidance totheir assessors in the form of Safety Assessment Principles (SAPs)15, whichnote varying levels of safety classification. The specification of the weldingquality and inspection regime will be related to its safety classification. Thiswill also determine the required competences and knowledge of thewelders, engineers and non-destructive testing (NDT) specialists.

To develop industry-agreed role profiles capturing the technical and safetycompliance competences, the concept of Job Contexts has been developedby Cogent Sector Skills Council16. Cogent has drafted Job Contexts for thecompetences needed for welding roles, to provide assurance of skills levelsto avoid the quality shortfalls identified in the main lessons learned report.

While the welding Job Contexts provide a framework for defining therequired competences, the detailed welding requirements for new build(per reactor type and construction method) are not yet known and thus theframework cannot be fully populated.

Recommendation 8

As soon as is practicable, the industry, via relevant skills bodies, needsto define detailed welding skills requirements for nuclear new buildfrom which training courses and certification schemes can be designed.This will give the supply chain certainty of which training to undertake.

Beyond particular welding skills issues, the working group perceived a lackof clarity on the national strategy for nuclear skills, noting that there are upto 15 separate skills organisations in the nuclear ‘space’. The key nuclearskills bodies in this space are:

• Cogent as the Sector Skills Council and standards-setting body for thenuclear industry.

• The Engineering Construction Industry Training Board (ECITB) as thestatutory levy board for the engineering construction industry with directresponsibility for national occupational standards for onsite welding.

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• SEMTA as the Sector Skills Council with responsibility for nationaloccupation standards including welding in a manufacturing environment.

• The National Skills Academy for Nuclear (NSAN) which is the leadstrategic body that represents the industry to stimulate, coordinate andenable excellence in skills to support the nuclear programme.

The working group determined that the skills issue required a degree of‘top down’ direction in order to ensure that the UK has the necessary skillsfor new build.

Recommendation 9

A new single integrated skills structure is required that includesgovernment, relevant industry skills bodies, employers (site operatorsand supply chain), training providers and certifying bodies. This woulddefine clearly (possibly by extending the Nuclear Skills Passport) thecommon and prioritised skills required for core engineering andconstruction occupations associated with nuclear new build (such aswelding). It should provide clear points of access to advice on skillsrequirements and funding, particularly for SMEs and could address theissues highlighted in this report of apprenticeships, migrant labour andre-skilling of existing workers.

The Nuclear Energy Skills Alliance, comprising BIS, DECC, NSAN, ECITB,Construction Skills, SEMTA, Cogent and NDA, can fulfil this role as itbrings together all the relevant stakeholders in this area with clear terms ofreference and SMART objectives17.

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4. Introduction of newtechnology

On one of the construction projects analysed in the original Nuclear LessonsLearned1 report, problems in the deployment of new technology duringmanufacture of the Reactor Pressure Vessel (RPV) were encountered,leading to additional inspection and repair welding. The working groupidentified the successful deployment of new welding technologies as acritical element in delivering right-first-time manufacturing of nuclear newbuild projects, from major critical components such as RPVs,manufactured by top-tier suppliers, to downstream components fabricatedby small and medium sized enterprises (SMEs).

New welding technology in this context does not necessarily mean thedeployment of new welding processes, necessitating code changes, but canmean automating a welding process previously performed manually.However, it is recognised that operators want proven technology appliedwell and therefore care should be taken where and when new technology isapplied if benefits are to be realised.

Applied well, the benefits of introducing new welding technologies areimproved quality and reliability of welded joints; reduction of cost over thelong term through less reliance on manual labour; increased attractivenessof welding as a career through use of advanced technologies; improvedproductivity and facilitation of the use of new and advanced materials intomanufactured products.

The working group concluded that, while use of new technology is highlydesirable where applicable, there are barriers to its implementation. Whilethe UK government’s promotion of a ‘fleet’ approach to new build maymitigate this, uncertainty in the fabrication supply chain over the timing ofnew build contracts is delaying investment in, and adoption of, newtechnologies, particularly among SMEs. As a consequence, the benefits ofnew technology may be missed.

The problems identified with liner welding could be resolved throughproduction of mock ups of key sections of thin plate with heavyembedment fitted to prove that they could control distortion. This is in linewith RCC-M works approval philosophy, but a similar philosophy does notexist in ASME. Hence a suitable approach would be to ensure that bestpractice and lessons learned in these areas are shared across the sites, andin a collaborative manner. A lack of awareness in the nuclear industry,particularly among smaller companies, of what technologies can do ishampering adoption. Many fabricators lack the capacity, time andinformation to evaluate possible new approaches and communication withother sectors on transferable technologies is patchy.

The introduction of new technology to welding operations in the supplychain will necessitate new training and certification schemes in order tohave the right numbers of appropriately skilled staff in place.

Recommendation 10

There should be industry coordination of the development andimplementation of new welding technologies and associated skills inorder to realise benefits in weld quality.

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While examples of good practice exist among larger companies, amongmany smaller companies there is a lack of knowledge of how to managethe successful introduction of new welding technology in a manufacturingenvironment. Furthermore, introducing new technologies is inherently riskywith large up-front capital costs. Most companies see the benefits butmany do not want to be the first to adopt. Rolls Royce’s ManufacturingCapability Readiness Level system is an example of good practice thatcould be used in this way, potentially for Generation III and certainly forGeneration IV reactor designs.

Recommendation 11

A rigorous and collaborative system to manage the introduction of newtechnology, that reduces the cost and risk of adoption by smallercompanies, is needed. Top-tier companies (in collaboration withregulators, operators and research bodies such as the NuclearAdvanced Manufacturing Research Centre) could ‘own’ the system andshare most of the risk, such as the costly and time-consuming processof driving a code change. Ready to deploy technologies could be thencascaded to suppliers who potentially could share resources and capitalinvestment.

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5. ConclusionsThe working group examined the original Nuclear Lessons Learned1 reportfrom a welding perspective. While it contained only brief information onthe nature of welding issues in the build projects reviewed, the workinggroup identified three linked areas for analysis and recommendation:welding quality assurance, welding skills, and introducing new weldingtechnology. Encouragingly, there is already evidence of learning fromcurrent build projects around the world being applied by operators,technology vendors and major supply chain companies planning UK newbuild, driven by the standard design philosophy of the nuclear planttechnologies and ‘fleet’ approach promoted by the UK government. Therecommendations in this report are intended to support these efforts.

The prevalence of fabricated metallic components in nuclear power plantsmeans that welding is critical for their successful construction and safeoperation. Ensuring welding quality is challenging as it cannot beadequately inspected in the finished product and must be assured by closecontrol of the welding operation and its associated activities. Furthermore,a tiered approach to quality must be taken such that any systemimplemented is appropriate to the safety criticality of each component.Learning from approaches to welding quality taken in other industries (forexample aerospace and oil and gas) could be beneficial to the UK nuclearnew build programme, particularly with implementing consistent systemsthrough the whole supply chain.

High quality welding is critically dependent on having sufficient suitablyqualified and demonstrably competent personnel at all levels of the supplychain. This includes craft welders and related occupations such as weldingsupervisors, welding coordinators and welding engineers. Welding isrecognised as an area at high risk of skills shortage, with an ageing andretiring demographic. Work initiated by nuclear skills agencies should beextended to specify competence and qualification requirements for weldingroles, and measures taken to further encourage the supply chain(particularly small companies) to invest in up-skilling and apprenticeships.

Finally, lessons need to be learned from recent nuclear build projects toensure the optimum deployment of new welding technologies. While theycan bring many cost and quality benefits, suppliers (particularly SMEs) aredelaying investment because of uncertainty over the timing of new buildcontracts. Beyond this, technology implementation needs to be handledcarefully and managed alongside the development of new workforce skills.The industry, driven by top-tier suppliers, may be able to adopt existinggood practice from other sectors through the use of a stage gatetechnology deployment system.

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AcknowledgementsLead authors:

Sayee Raghunathan (TWI Ltd)

Paul Jones (TWI Ltd)

Working group members:

John Beecroft (Nuclear Power Delivery UK)

Martyn Fletcher (Doosan Babcock)

Andrew Goodfellow (EDF Energy)

Les Higham (Nuclear Power Delivery UK)

Dr Steven Jones (Rolls-Royce)

Rob Newton (Lloyd’s Register)

Bob Pennycook (Lloyd’s Register)

Ian Simpson (Performance Review Institute)

Clive Smith (Cogent Sector Skills Council)

Kevin Smith (Nuclear Power Delivery UK)

James Steady (Performance Review Institute)

Keith Waller (Department of Energy & Climate Change)

Andy Wilby (EDF Energy)

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7 AFCEN www.afcen.org/index.php?menu=vocation_en

8 NRC Regulations Title 10, Code of Federal Regulationswww.nrc.gov/reading-rm/doc-collections/cfr/

9 Quality Assurance Requirements for Nuclear Facility Applications (QA)NQA-1 – 2004 www.asme.org/products/codes---standards/quality-assurance-requirements-for-nuclear-fac-(2)

10 ASME Rules for construction of nuclear power plant componentswww.asme.org/kb/standards/bpvc-resources/boiler-and-pressure-vessel-code---2010-edition/iii--rules-for-construction-of-nuclear-power-plant

11 ASME Power Piping B31.1 – 2010 www.asme.org/products/codes---standards/power-piping-(1)

12 An Overview of QA/QC Requirements in present NPP projects (July2009) www.afcen.org/generalites/PVP2009-78036.pdf

13 www.cogent-ssc.com/research/nuclearresearch.php

14 www.ukba.homeoffice.gov.uk/sitecontent/documents/aboutus/workingwithus/mac/mac-analysis-of-pbs/report.pdf?view=Binary

15 www.hse.gov.uk/nuclear/saps/saps2006.pdf

16 www.cogent-ssc.com/industry/nuclear/nitfjs.php#2

17 NESA’s terms of reference are available atwww.decc.gov.uk/assets/decc/11/meeting-energy-demand/nuclear/4036-nuclear-energy-skills-alliance-terms-ref.pdf

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We provide independent expert advice and promote understanding of the contribution thatengineering makes to the economy, society and to the development and delivery of national policy.

The leadership of Engineering the Future is drawn from the following institutions:

The Engineering Council; EngineeringUK; The Institution of Chemical Engineers; The Institution ofCivil Engineers; The Institution of Engineering and Technology; The Institution of MechanicalEngineers; The Institute of Physics; The Royal Academy of Engineering.

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Nuclear Construction Use of Welding